CVE-2023-45818 — tinymce
MEDIUMCVE-2023-45818 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in tinymce. A fix is available for tinymce — see the affected versions and patch details below.
Cross-site Scripting vulnerability in TinyMCE undo/redo, getContent API, resetContent API, and Autosave plugin
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-45818.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
tinymcenpmDescription
Impact
A mutation cross-site scripting (mXSS) vulnerability was discovered in TinyMCE’s core undo and redo functionality. When a carefully-crafted HTML snippet passes the XSS sanitisation layer, it is manipulated as a string by internal trimming functions before being stored in the undo stack. If the HTML snippet is restored from the undo stack, the combination of the string manipulation and reparative parsing by either the browser's native DOMParser API (TinyMCE 6) or the SaxParser API (TinyMCE 5) mutates the HTML maliciously, allowing an XSS payload to be executed. This vulnerability also impacts these related TinyMCE APIs and plugins:
Patches
This vulnerability has been patched in TinyMCE 5.10.8 and TinyMCE 6.7.1 by ensuring HTML is trimmed using node-level manipulation instead of string manipulation.
Fix
To avoid this vulnerability:
- Upgrade to TinyMCE 5.10.8 or higher for TinyMCE 5.x.
- Upgrade to TinyMCE 6.7.1 or higher for TinyMCE 6.x.
Acknowledgements
Tiny Technologies would like to thank Masato Kinugawa of Cure53 for discovering this vulnerability.
References
For more information
If you have any questions or comments about this advisory:
- Email us at [email protected]
- Open an issue in the TinyMCE repo
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | tinymce | ≥ 6.0.0&&< 6.7.1 | 6.7.1npm install tinymce@6.7.1 |
| 📦npm | tinymce | all versions | 5.10.8npm install tinymce@5.10.8 |
| .NETNuGet | TinyMCE | ≥ 6.0.0&&< 6.7.1 | 6.7.1dotnet add package TinyMCE --version 6.7.1 |
| .NETNuGet | TinyMCE | all versions | 5.10.8dotnet add package TinyMCE --version 5.10.8 |
| 🐘Packagist | tinymce/tinymce | ≥ 6.0.0&&< 6.7.1 | 6.7.1composer require tinymce/tinymce:^6.7.1 |
| 🐘Packagist | tinymce/tinymce | all versions | 5.10.8composer require tinymce/tinymce:^5.10.8 |
Affected Products
tinymcetinyDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for tinymce, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update tinymce to 6.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-45818 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2023-45818 in your dependencies?
Find it across npm, NuGet, Packagist, including transitive dependencies.